Code to generate graph paper in SVG with Perl

graph_paper.pl

#!/usr/bin/env perl

use strict ;
use warnings ;
use utf8 ;
use feature qw{ postderef say signatures state } ;
no warnings qw{ experimental::postderef experimental::signatures } ;

use Carp ;
use Getopt::Long ;
use Pod::Usage ;    # when I fix my man/help screens
use SVG ;

my $config = config() ;

my $svg = SVG->new(
    height => $config->{ height },
    width  => $config->{ width },
    ) ;

if ( $config->{ dot } ) {
    my $height = $config->{ height } ;
    my $width  = $config->{ width } ;
    my $step   = $config->{ step } ;

    for ( my $h = 0 ; $h <= $height ; $h = $h + $step ) {
        for ( my $v = 0 ; $v <= $width ; $v = $v + $step ) {
            $svg->circle(
                cx    => $v,
                cy    => $h,
                r     => 0.5,
                style => {
                    stroke         => 'black',
                    'stroke-width' => 0.2,
                    fill           => 'black',
                    }
                    ) ;
            }
        }

    say 'DOT' ;
    }
else {
    say 'LINE' ;
    my $height = $config->{ height } ;
    my $width  = $config->{ width } ;
    my $step   = $config->{ step } ;

    # horizontal
    for ( my $h = 0 ; $h <= $height ; $h = $h + $step ) {

        # say join ', ', 'Horizontal', 0, $h, $width, $h ;
        $svg->line(
            x1    => 0,
            y1    => $h,
            x2    => $width,
            y2    => $h,
            style => {
                stroke         => 'black',
                'stroke-width' => 0.2,
                fill           => 'none',
                }
                ) ;
        }

    # vertical
    for ( my $v = 0 ; $v <= $width ; $v = $v + $step ) {

        # say join ', ', 'Vertical', $v, 0, $v, $height ;
        $svg->line(
            x1    => $v,
            y1    => $0,
            x2    => $v,
            y2    => $height,
            style => {
                stroke         => 'black',
                'stroke-width' => 0.2,
                fill           => 'none',
                }
                ) ;
        }
    }

my $output = $svg->xmlify ;
if ( open my $fh, '>', $config->{ file } ) {
    print $fh $output ;
    close $fh ;
    say 'Done' ;
    }
else {
    say 'fail' ;
    }

exit ;

sub config () {
    my $config = {
        dot    => 0,
        height => 600,
        width  => 600,
        step   => 10,
        file   => 'graph.svg',
        } ;
    GetOptions(
        'man'      => \$config->{ man },
        'height=i' => \$config->{ height },
        'width=i'  => \$config->{ width },
        'step=i'   => \$config->{ step },
        'dot'      => \$config->{ dot },
        'file=s'   => \$config->{ file },
        ) ;

    exit if $config->{ height } < 100 ;
    exit if $config->{ width } < 100 ;
    exit if $config->{ step } < 1 ;
    exit if $config->{ man } ;
    return $config ;
    }

__DATA__

COPYRIGHT & LICENSE
    Copyright 2018 - Dave Jacoby

    This code is distributed under the same license
    as Perl itself. It is provided free of warranty 
    and may be re-used freely.